A big brother's decision to bring his begging five-year-old sister Miaomiao on the twenty-hour train ride back to university after summer vacation becomes the biggest regret of his life.
Thrilled to see her brother's school, the little girl chatters like a little magpie and marvels at everything until she suddenly needs the bathroom.
He waits right outside while she goes in, but soon gets distracted reading a short story on his phone.
When a dark-faced middle-aged man impatiently opens the door, the locked, windowless bathroom is completely empty—Miaomiao has vanished.
How could she disappear from a sealed space right under her brother's watch?
